TNF related activation induced cytokine (TRANCE; also known as RANK L, OPGL, and ODF) is a 35kD (predicted) type II transmembrane glycoprotein and member of the TNF cytokine family. Human TRANCE is 317 amino acids (aa) in length and contains a 47 aacytoplasmic region, a 21aa transmembrane region, and a 249aa extracellular domain (ECD), which contains two potential sites of N-linked glycosylation. Alternative splicing produces three isoforms of human TRANCE. Isoform 1 is the standard form. Isoform 2 is missing amino acids 1-73 of isoform 1, and isoform 3 is missing amino acids 1-47 of isoform 1. The extracellular domain of human TRANCE is 83% identical to the extracellular domain of mouse TRANCE. TRANCE is most highly expressed in the peripheral lymph nodes, but is also expressed at lower levels in the spleen, peripheral blood leukocytes, bone marrow, heart, placenta, skeletal muscle, stomach, and thyroid. TRANCE plays a role in osteoclast differentiation and activation.